Do not re-export _Unwind_XXX symbols.

Bug: 130267141

Test: All system shared libraries do not contain global _Unwind_XXX symbols.
Change-Id: I79673753bb8197041bfe8ffb016d9f5fdf4cada5
Merged-In: I79673753bb8197041bfe8ffb016d9f5fdf4cada5
(cherry picked from commit cf78867417)

cc/config/global.go

@@ -83,6 +83,7 @@ var (
 		"-Wl,--warn-shared-textrel",
 		"-Wl,--fatal-warnings",
 		"-Wl,--no-undefined-version",
+		"-Wl,--exclude-libs,libgcc.a",
 	}
 
 	deviceGlobalLldflags = append(ClangFilterUnknownLldflags(deviceGlobalLdflags),

cc/stl.go

@@ -245,7 +245,10 @@ func (stl *stl) flags(ctx ModuleContext, flags Flags) Flags {
 		ndkSrcRoot := android.PathForSource(ctx, "prebuilts/ndk/current/sources/cxx-stl/system/include")
 		flags.CFlags = append(flags.CFlags, "-isystem "+ndkSrcRoot.String())
 	case "ndk_libc++_shared", "ndk_libc++_static":
-		// Nothing.
+		if ctx.Arch().ArchType == android.Arm {
+			// Make sure the _Unwind_XXX symbols are not re-exported.
+			flags.LdFlags = append(flags.LdFlags, "-Wl,--exclude-libs,libunwind.a")
+		}
 	case "":
 		// None or error.
 		if !ctx.toolchain().Bionic() {